1. Field of the Invention
The present invention relates to a multi-view picture encoding and decoding apparatus, and more particularly, to a disparity vector estimation method of quickly encoding a multi-view picture and improving the compressibility of the multi-view moving picture, and an apparatus for encoding and decoding a multi-view picture using the disparity vector estimation method.
2. Description of the Related Art
Recently, a new H.264 picture coding video coding standard for high encoding efficiency compared to conventional standards has been developed. The new H.264 picture coding standard depends on various characteristics, consideration of a variable block size between 16×16 and 4×4, a quadtree structure for motion compensation using a loop de-blocking filter, a multi-reference frame, intra prediction, and context adaptability entropy coding, as well as consideration of general bi-directional (B) estimation slices. Unlike the MPEG-2 standard, the MPEG-4 Part 2 standard, etc., the B slices can be referred to as different slices while using multi-prediction obtained from the same direction (forward or backward). However, the above-described characteristics require many bits for encoding motion information including an estimation mode and motion vector and/or reference image.
In order to overcome this problem, a skip mode and a direct mode can be respectively introduced into predicted (P) slices and B slices. The skip and direct modes allow motion estimation of an arbitrary block of a picture to be currently encoded, using motion vector information previously encoded. Accordingly, additional motion data for blocks or macroblocks (MBs) is not encoded. Motions for these modes are obtained using spatial (skip) or temporal (direct) correlation of motions of adjacent MBs or pictures.
FIG. 1 is a view for explaining a direct mode of a B picture.
In the direct mode, a forward motion vector and a backward motion vector are obtained using a motion vector of a co-located block of a temporally following P image, when estimating a motion of an arbitrary block of a B picture to be currently encoded.
In order to calculate a forward motion vector MVL0 and a backward motion vector MVL1 of a direct mode block 102 whose motion will be estimated in a B picture 110, a motion vector MV for a reference list 0 image 130 is detected. A motion vector refers to the reference list 0 image 130 which a co-located block 104 of a temporally following picture vector. The co-located block 104 is at the same position as the direct mode block 102 in a current B. Thus, the forward motion vector MVL0 and the backward motion vector MVL1 of the direct mode block 102 of the B picture 110 are calculated using Equations 1 and 2 as follows.
                                          MV            →                                L            ⁢                                                  ⁢            0                          =                                            TR              B                                      TR              D                                ×                      MV            →                                              (        1        )                                                      MV            →                                L            ⁢                                                  ⁢            1                          =                                            (                                                TR                  B                                -                                  TR                  D                                            )                                      TR              D                                ×                      MV            →                                              (        2        )            where MV represents the motion vector of the co-located block 104 of the reference list 1 picture 120, TRD represents a distance between the reference list 0 picture 130 and the reference list 1 picture 120, and TRB represents a distance between the B picture 110 and the reference list 0 picture 130.
FIG. 2 is a view for explaining a method of estimating a motion vector in a spatial area.
According to the H.264 standard used for encoding moving motion picture data, a frame is divided into blocks, each having a predetermined size, and motion searching for a most similar block to an adjacent frame(s) subjected to encoding is performed. That is, an intermediate value of motion vectors of a left macroblock 4, an upper middle macroblock 2, and an upper right macroblock 3 of a current macroblock c is determined as an estimation value of the corresponding motion vector. The motion vector estimation can be expressed by Equation 3 as follows.
                    {                                                            pmvx                =                                  MEDIAN                  ⁢                                                                          ⁢                                      (                                                                  mvx                        ⁢                                                                                                  ⁢                        2                                            ,                                              mvx                        ⁢                                                                                                  ⁢                        3                                            ,                                              mvx                        ⁢                                                                                                  ⁢                        4                                                              )                                                                                                                          pmvy                =                                  MEDIAN                  ⁢                                                                          ⁢                                      (                                                                  mvy                        ⁢                                                                                                  ⁢                        2                                            ,                                              mvy                        ⁢                                                                                                  ⁢                        3                                            ,                                              mvy                        ⁢                                                                                                  ⁢                        4                                                              )                                                                                                          (        3        )            
As such, a method of encoding a moving picture using spatial correlation as well as temporal correlation has been proposed. However, a method of enhancing the compressibility and processing speed of a multi-view picture having significantly more information than a general moving motion picture, is still required.